Connection oriented point-to-point communication links, such as a Layer 2 Tunneling Protocol (L2TP) tunnel, are an increasingly common feature of network infrastructures. Tunnels are prearranged connections established by agreement between interne service providers (ISPs). See Request for Comment (RFC) 2661 and Layer Two Tunneling Protocol (L2TP), A. Valencia, et al., draft-ietf-pppext-12p-16.text, June 1999, herein incorporated by reference, available from the Internet Engineering Task Force (IETF) at World Wide Web.ietf.org for more information. FIG. 1 shows an architecture 10 that illustrates two L2TP tunnels 56 and 66 established through a public IP network 70. Each L2TP tunnel is a prearranged point to point link between remote client 20 and server 80.
An L2TP tunnel provides a conduit for communications between a remote client 20 and a server 80. Typically, a single tunnel slot provides the communication link between a client and server. However, it is increasingly common for there to be multiple tunnels providing the client-server communication link. For example, Multi-Link Point-to-Point (MLPPP) connections aggregate the bandwidth of multiple tunnel connections to provide a single higher bandwidth communication link. Also, in wireless mobile applications, a second tunnel link may be established from a tunnel initiator in the cell area that the client is entering while a first tunnel link still exists from the tunnel initiator in the cell area that the client is leaving. It is advantageous in such multiple link connections to have each link terminate on the same tunnel endpoint. However, there is no conventional way to deterministically select the endpoint for a given L2TP tunnel.
When remote client 20 establishes a dial-up connection 22 or 24 with a tunnel initiator (TI) 30 or 40, then the TI typically recognizes client 20 as a tunnel client by means of an authentication protocol, such as RADIUS, see Request For Comment (RFC) 2138, herein incorporated by reference, or other means for identifying the client. Typically, each TI has a table that indicates the endpoint for the tunnel connection for client 20. The table in each TI typically includes a list of tunnel endpoints (TEs), such as 50 and 60 for each remote client and each TI selects an endpoint from the list independent of the selection made by another TI. Similarly, TI 40 will have a table that indicates a list of endpoints for client 20. When client 20 connects to TI 30 or 40, then each TI will independently select a TE device. As a result, there is a high likelihood that the two tunnel connections 56 and 66 will terminate on different tunnel endpoint devices, as is shown in FIG. 1.
Thus, the need remains for a method for terminating tunnels initiated on multiple tunnel initiators on a common tunnel endpoint.